Pile fabrics have been used for clothing or the like as they enhance the design of appearance. However, there has been a problem in use of the pile fabric, namely, the garments become undesirably heavy even though the appearance is enhanced.
In order to cope with this problem, porous fibers have been used for the fiber to form the pile fabric. For example, Patent document 1 suggests making fibers porous by subjecting an acrylic fiber prepared by blending a hydrophilic polymer soluble in an organic solvent used for spinning to a wet-heat treatment, and manufacturing a lightweight pile fabric by use of the fiber.
In some cases, the fiber at a napped portion of a pile fabric is dyed for a design. At the time of dyeing, sometimes the fabric is steamed as required. Or a part of the dyestuff fixed to the fiber at the napped portion is degraded and then another dyestuff of a different color may be coated thereon. This method is advantageous since the design at the napped portion of the pile fabric is improved and the appearance more closely resembles to that of animal hair. In general, a step of degrading a part of the dyestuff with a discharging agent is called a “discharging step”, and a step of coating a print dyestuff is called a “printing step”. During these steps, for the purpose of making the discharging agent and the print dyestuff penetrate into the fibers at the napped portion, a steam treatment is conducted.